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Bootable Linux USB stick: Difference between revisions
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TRIMming informs the firmware about blocks of the filesystem that do not contain file data. This is available for USB sticks for which <code>hdparm -I /dev/sdX</code> returns "Data Set Management TRIM supported". | TRIMming informs the firmware about blocks of the filesystem that do not contain file data. This is available for USB sticks for which <code>hdparm -I /dev/sdX</code> returns "Data Set Management TRIM supported". | ||
The <code>wiper.sh</code> script (part of the <code>hdparm</code> source distribution) TRIMs ext3/ext4/xfs filesystems, but does not reproducibly seem to work for our preferred SanDisk Extreme 32GB stick if the filesystem is mounted. This is probably due to the fact that this stick has a limitation of max 65536 blocks in one TRIM command (https://sourceforge.net/p/hdparm/bugs/63/). Since <code>wiper.sh</code> also works for unmounted filesystems, and the mapping of unused space is then obtained with a different tool, one should try with an unmounted filesystem as well - this worked for us in | The <code>wiper.sh</code> script (part of the <code>hdparm</code> source distribution) TRIMs ext3/ext4/xfs filesystems, but does not reproducibly seem to work for our preferred SanDisk Extreme 32GB stick if the filesystem is mounted. This is probably due to the fact that this stick has a limitation of max 65536 blocks in one TRIM command (https://sourceforge.net/p/hdparm/bugs/63/). Since <code>wiper.sh</code> also works for unmounted filesystems, and the mapping of unused space is then obtained with a different tool, one should try with an unmounted filesystem as well - this worked for us in some cases (tested with [http://lightrush.ndoytchev.com/random-1/checkiftrimonext4isenabledandworking this script]). | ||
All other methods, like the <code>fstrim</code> command and the <code>discard</code> mount option '''do not work for USB sticks''', because the usb-storage kernel module does not pass the ATA TRIM command through the USB bridge and controller to the device. The same goes for [http://unix.stackexchange.com/questions/97143/utility-to-trim-unallocated-space-on-drive <code>blkdiscard</code>]. | All other methods, like the <code>fstrim</code> command and the <code>discard</code> mount option '''do not work for USB sticks''', because the usb-storage kernel module does not pass the ATA TRIM command through the USB bridge and controller to the device. The same goes for [http://unix.stackexchange.com/questions/97143/utility-to-trim-unallocated-space-on-drive <code>blkdiscard</code>]. | ||